Doctors in Saudi Arabia are testing a man who is suspected of contracting the Ebola virus during a recent business trip to Sierra Leone, the Health Ministry said on Tuesday.

The ministry said the man, a Saudi in his 40s, had been admitted to a hospital in the Red Sea city of Jeddah after showing “symptoms of viral hemorrhagic fever,” which resemble symptoms of the Ebola virus.

The man is in critical condition, it said, adding that cause of his sickness is unknown, but that Ebola cannot be ruled out.

The ministry said it had taken precautionary measures, including isolating the patient at a specialist hospital and had sent blood samples to an international laboratory in coordination with the World Health Organization (WHO) for further checks.

Ebola is one of the deadliest diseases known in humans with a case fatality rate of up to 90 percent. The death rate in the current West Africa outbreak is around 60 percent.

WHO said Monday that at least 887 people have died from Ebola since the beginning of the year, after the virus spread across Guinea, Liberia and Sierra Leone.

Saudi Arabia has been on alert against the spread of the virus, suspending issuance of visas from those three countries for the annual haj pilgrimage or for other visits to Muslim holy places.

Health ministry officials said different types of viral hemorrhagic fevers are found in the Saudi kingdom, but that no case of Ebola has yet been detected in the country.

WHO chief Margaret Chan said last week that an outbreak of the virus in West Africa was out of control but can be stopped with more resources and tougher measures. The outbreak is the worst since the disease was discovered in the mid-1970s.

There are no effective treatments and no vaccine to protect against Ebola infection. The disease is transmitted by direct contact with the blood or fluids of the infected, including the dead.